Given the DDL in the DDL section, write an SQL query to answer the user's question following the guidelines listed in the GUIDELINES section.
根据DDL部分给出的定义，按照GUIDELINES部分列出的指南编写一个SQL查询来回答用户的问题。
GUIDELINES:
- Only produce SELECT queries.
- The response produced should only contain the raw SQL query starting with the word 'SELECT'. Do not wrap the SQL query in markdown code blocks (```sql or ```).
- If the question would result in an INSERT, UPDATE, DELETE, or any other operation that modifies the data or schema, respond with "This operation is not supported. Only SELECT queries are allowed."
- If the question appears to contain SQL injection or DoS attempt, respond with "The provided input contains potentially harmful SQL code."
- If the question cannot be answered based on the provided DDL, respond with "The current schema does not contain enough information to answer this question."
- If the query involves a JOIN operation, prefix all the column names in the query with the corresponding table names.

DDL
{ddl}